Luminescent material

ABSTRACT

A luminescent material is disclosed. The luminescent material may include a first compound having a host lattice comprising first ions and oxygen. A first portion of the first ions may be substituted by copper ions. In one embodiment, the host lattice may include silicon, the copper ions may be divalent copper ions and the first compound may have an Olivine crystal structure, β-K .2 SO 4  crystal structure, a trigonal Glaserite (K 3 Na(SO 4 ) 2 ) or monoclinic Merwinite crystal structure, a tetragonal Ackermanite crystal structure, a tetragonal crystal structure or an orthorhombic crystal structure. In another embodiment, the copper ions do not act as luminescent ions upon excitation with the ultraviolet or visible light.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/948,813, filed on Nov. 30, 2007, which is acontinuation-in-part of U.S. patent application Ser. No. 11/024,722,filed on Dec. 30, 2004, and claims priority from and the benefit ofKorean Patent Application No. 10-2004-0042397, filed on Jun. 10, 2004,which is hereby incorporated by reference for all purposes as if fullyset forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate generally to fluorescentmaterials containing rare earth elements and, more particularly, to suchluminescent materials for exciting ultraviolet as well as visible lightcontaining lead- and/or copper-containing compounds.

2. Description of the Related Art

Lead and copper activated materials are known for short wave excitation,e.g. from a low pressure mercury lamp, such as barium disilicateactivated by lead (Keith H. Butler, The Pennsylvania State UniversityPress, 1980, S 175, orthosilicate activated by lead (Keith H. Butler,The Pennsylvania State University Press, 1980, S. 181), akermanitesactivated by lead, or Ca-metasilicate activated by Pb²⁺.

Generally, the maxima of the emission bands of such lead activatedphosphors are located between 290 nm and 370 nm at 254 nm excitation.Bariumdisilicate activated by lead is an U.V. emitting phosphor whichcurrently is used in sun parlor lamps.

Lead has in the ground state ¹S₀ two outer electrons. The electronconfiguration of the ground state is d¹⁰s², so that the lowest excitedstate has d¹⁰sp configuration. The excited sp configuration has fourlevels, ³P₀, ³P₁, ³P₂ and ¹P₁, which can be achieved between 165.57 nm(³P₀) and 104.88 nm (¹P₁) in the free ion. Transitions between ¹S₀ and¹P₁ excited level are allowed by all selection rules. While transitionsbetween ¹S₀ and ³P₀ are only allowed with the lowest symmetry,transitions between ¹S₀ and ³P₁ as well as ³P₂ are allowed only undercertain conditions. However, excitation between 180 and 370 nm has thesame emission. Excitation with wavelength longer than 370 nm is notpossible.

Otherwise, luminescent materials are known having lead as a host latticecomponent. Molybdate phosphors containing MoO₄ ²⁻ centers are describedin Bernhardt, H. J., Phys. Stat. Sol. (a), 91, 643, 1985. PbMoO₄ showsat room temperature red emission with an emission maximum at 620 nmunder photoexcitation at 360 nm.

However, such emission is not caused by lead itself. In molybdates theluminescence properties are not caused by the metal ion M²⁺ (M²⁺MoO₄where M²⁺=Ca, Sr, Cd, Zn, Ba, Pb etc). Here, defect centers of MoO₄ ²⁻ions coupled to O²⁻-ion vacancies seem to be the reason. Nevertheless,the Pb²⁺-ion influences the preferred emission properties because itstabilizes the host lattice.

As a familiar example, tungstates (Ca,Pb)WO₄ as mixed crystals have astrong green emission with high quantum output of 75% (Blasse, G,Radiationless processes in luminescent materials, in RadiationlessProcesses, DiBartolo, B., Ed. Plenum Press, New York, 1980, 287). Under250 nm excitation PbWO₄ shows blue emission and under 313 nm excitationPbWO₄ has an orange emission band, which can be caused by Schottkydefects or by impurity ions (Phosphor Handbook, edited under the Auspiceof Phosphor Research Society, CRC Press New York, 1998, S 205).

Copper was used as a monovalent activator in orthophosphates (Wanmaker,W. L. and Bakker, C., J. Electrochem. Soc., 106, 1027, 1959) with anemission maximum at 490 nm. The ground state of monovalent copper is afilled shell 3d¹⁰. That is the level ¹S₀. After exciting the lowestexcited configuration is 3d⁹4s. This configuration has two terms, ³D and¹D. The next higher configuration, 3d⁹4p, gives 6 terms ³P°, ³F°, 3D°,¹F°, ¹D° and ¹P°. The transitions between the ground state ¹S₀ and the¹D or ³D are forbidden by parity or spin, respectively. In copper ions,the excitation to the crystal field levels of 4p terms are allowed.Emission will be got either by a direct return from the crystal fieldodd state to the ground state or by a combination of transitions firstfrom the odd state to a crystal field level and after that a secondtransition from these ³D or ¹D state of the 3d⁹4s configuration to theground state.

The ground state of bivalent copper has 3d⁹-configuration. That is thelevel ²D_(5/2). In the bivalent copper, one of the d-electrons can beexcited to the 4s or 4p orbital. The lowest exciting configuration isthe 3d⁸4s with two quartet terms ⁴F, ⁴P and four doublet terms, ²F, ²D,²P and ²G without emission caused by forbidden transitions. The higherexciting configuration is the 3d⁸4p-configuration with four terms ⁴D°,⁴G°, ⁴F°, and ⁴P°, where emission can occur.

Copper activated or co-activated sulphide-phosphors are well known andthey are commercial used for cathode ray tubes. The green-emittingZnS:Cu, Al (wherein, the copper is used as activator and Al is used asco-activator) is very important in CRT applications.

In zinc-sulphide phosphors, the luminescent materials can be classifiedinto five kinds, depending on the relative ratio of the concentration ofactivators and co-activators (van Gool, W., Philips Res. Rept. Suppl.,3, 1, 1961). Here, the luminescent centers are formed from deep donorsor deep acceptors, or by their association at the nearest-neighbor sites(Phosphor Handbook, edited under the Auspice of Phosphor ResearchSociety, CRC Press New York, 1998, S. 238).

Orthophosphates activated by copper (Wanmaker, W. L., and Spier, H. L.,JECS 109 (1962), 109), and pyrophosphates, alumosilicates, silicates,and tripolyphosphates all activated by copper are described in “Keith H.Butler, The Pennsylvania State University Press, 1980, S. 281”. However,such phosphors can only be used for a short wave U.V. excitation.Because of their unstable chemical properties and their temperaturebehavior, they cannot be used in fluorescent lamps.

It has been observed that conventional luminescent materials aregenerally unstable in water, air humidity, water steam and polarsolvents.

SUMMARY OF THE INVENTION

One embodiment exemplarily described herein can be generallycharacterized as a luminescent material for a light emitting diode (LED)that includes a first compound including a host lattice and aluminescent ion within the host lattice. The host lattice may includefirst ions and oxygen. A first portion of the first ions may besubstituted by divalent copper ions. The first compound may emit lightupon excitation with ultraviolet light or visible light emitted by theLED. The first compound may have an Olivine crystal structure, aβ-K_(.2)SO₄ crystal structure, a trigonal Glaserite (K₃Na(SO₄)₂) ormonoclinic Merwinite crystal structure, a tetragonal Ackermanite crystalstructure, a tetragonal crystal structure or an orthorhombic crystalstructure.

According to another embodiment, the luminescent ion includes at leastone of Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm, Yb and Lu. According to another embodiment, the firstcompound includes Ge. According to another embodiment, the luminescentmaterial further includes at least one second compound selected from thegroup consisting of an aluminate, a silicate, an antimonite, agerminate, a germinate-silicate and a phosphate. According to anotherembodiment, the luminescent material emits white light upon excitationwith ultraviolet light or visible light.

Another embodiment exemplarily described herein can be generallycharacterized as a luminescent material for a light emitting diode (LED)that includes a first compound including a host lattice and aluminescent ion within the host lattice. The host lattice may includefirst ions and oxygen. A first portion of the first ions may besubstituted by copper ions. The first compound may emit light uponexcitation with ultraviolet light or visible light emitted by the LED.However, the copper ions do not act as luminescent ions upon excitationwith the ultraviolet light or visible light. An additional object of thepresent invention is to provide lead and/or copper doped luminescentmaterials, which give high color temperature range about 2,000K to8,000K or 10,000K and CRI over 90 in LED.

DETAILED DESCRIPTION

According to embodiments exemplarily described herein, a luminescentmaterial may include one or more lead- and/or copper-containing chemicalcompounds. The luminescent material may be excited by UV and/or visible(e.g., blue) light. In some embodiments, the lead- and/orcopper-containing chemical compounds may be generally characterized asincluding a host lattice having anions and cations. In some embodiments,at least a portion of the cations are divalent cations. In someembodiments, the divalent cations include alkaline earth ions. In someembodiments, at least a portion of the divalent cations of the hostlattice are substituted by divalent lead and/or divalent copper ions.

As mentioned above, conventional luminescent materials are generallyunstable in water, air humidity, water steam and polar solvents.However, due to a higher covalency and a lower basicity, thesubstitutionally-incorporated divalent lead and/or divalent copper ionsin the host lattice of the chemical compound yields luminescentmaterials having improved resistance against water, air humidity andpolar solvents.

The divalent lead and/or divalent copper ions within the host lattice donot act as activators (also referred to herein as “luminescent ions”)and, therefore do not luminance. Rather, it has been found that theseions tend to influence the crystal field splitting as well as thecovalency of the chemical compound. As a result, the substitutionalincorporation of divalent lead and/or copper ions within the hostlattice tends to influence luminescent-optical properties of thechemical compounds so as to improve luminescent intensity and desirablyshift the emission maxima, color points, and shape of emission spectra.

It has been found that phosphors having chemical compounds that containsubstitutionally-incorporated divalent lead and/or divalent copper ionsshow improved emission intensities as compared with phosphors havingchemical compounds that do not contain substitutionally-incorporateddivalent lead and/or divalent copper ions.

In addition, it has been found that phosphors having chemical compoundsthat contain substitutionally-incorporated divalent lead and/or divalentcopper ions tend to show improved luminescent properties for excitationwavelength higher than about 360 nm. At excitation wavelengths higherthan about 360 nm, the divalent lead and/or divalent copper ions do notexhibit their own radiation transfers due to the energy levels of theirelectron configuration, so that any kind of exciting radiation cannot belost. Furthermore, by substitutionally incorporating divalent leadand/or divalent copper ions, the emission wavelength can be shifted tohigher or lower energies as desired.

Lead ions having an ionic radius of 119 μm can substitute the alkalineearth ions Ca having an ionic radius of 100 μm and Sr having an ionicradius of 118 μm very easily. The electro negativity of lead with 1.55is much higher than that of Ca (1.04) and Sr (0.99). The preparation ofsubstances containing lead is complicated due to the possibility of anoxidation of these ions in reducing atmospheres. For the preparation oflead-containing compounds, which need reducing atmosphere, specialpreparation processes are necessary.

The influence of substitutionally-incorporated divalent lead ions in thecrystal field on the shifting of emission characteristics depends uponthe substituted ions. When divalent lead ions substitute Sr or Ba inEu-activated aluminates and/or silicates, the emission maximum tends tobe shifted to longer wavelengths due to smaller ionic radii of Pb ascompared with the ionic radii of Ba and Sr. That leads to a strongercrystal field surrounding the activator ion.

A similar effect shows the substitution of divalent copper ions foralkaline earth ions. Here, an additional influence is effective. Due tothe higher ionic potential of copper as a quotient of ionic charge andionic radius compared to the bigger alkaline earth ions, the copper ionscan attract the neighboring oxygen ions stronger than the alkaline earthions. So the substitution of the bigger alkaline earth ions Ca, Sr andBa by copper leads to a stronger crystal field in the surrounding of theactivator ions, too. Thus, the shape of emission bands can beinfluenced, the shifting of the emission peak to longer wavelength isconnected in a broadening of the emission curves for band emission. Inaddition, it should be possible to increase the intensity of emission bysubstitution of ions copper and lead. Generally, the shifting ofemission peaks to longer or shorter wavelengths are desirable in thefield of LED lighting. Here, it is necessary to realize a fine tuning toget a special wavelength for desired color points as well as for betterbrightness of optical devices. By using cations, copper and lead, such afine tuning should be possible.

As described above, the luminescent material may include one or morechemical compounds such as, for example, aluminates, silicates,antimonates, germinates, germinate-silicates, and/or phosphates.Exemplary embodiments of these luminescent materials are described ingreater detail below.

Example 1

Luminescent materials for ultraviolet light or visible light excitationcomprise lead- and/or copper-containing aluminates exemplarilycharacterized according to the formula as follows:

a(M′O).b(M″₂O).c(M″X).dAl₂O₃.e(M′″O).f(M″″₂O₃).g(M′″″_(o)O_(p)).h(M″″″_(x)O_(y))  (1)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be oneor more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag,and/or any combination thereof; M′″ may be one or more divalentelements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or anycombination thereof; M″″ may be one or more trivalent elements, forexample, Sc, B, Ga, In, and/or any combination thereof; M′″″ may be Si,Ge, Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M″″″may be Bi, Sn, Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,Er, Tm, Yb, Lu, and/or any combination thereof; X may be F, Cl, Br, I,and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦2; 0<d≦8; 0<e≦4;0≦f≦3; 0≦g≦8; 0<h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

a(M′O).b(M″₂O).c(M″X).4−a−b−c(M′″O).7(Al₂O₃).d(B₂O₃).e(Ga₂O₃).f(SiO₂).g(GeO₂).h(M″″_(x)O_(y))  (2)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be oneor more monovalent elements, for example, Li, Na, K, Rb, Cs, Au, Ag,and/or any combination thereof; M′″ may be one or more divalentelements, for example, Be, Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or anycombination thereof; M″″ may be Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and any combination thereof;X may be F, Cl, Br, I, and any combination thereof; 0<a≦4; 0≦b≦2; 0≦c≦2;0≦d≦1; 0≦e≦1; 0≦f≦1; 0≦g≦1; 0<h≦2; 1≦x≦2; and 1≦y≦5.

The preparation of copper- as well as lead-containing luminescentmaterials may be a basic solid state reaction. Pure starting materialswithout any impurities, e.g. iron, may be used. Any starting materialwhich may transfer into oxides via a heating process may be used to formoxygen dominated phosphors.

Examples of Preparation:

Preparation of the Luminescent Material Having Formula (3)

Cu_(0.02)Sr_(3.98)Al₁₄O₂₅:Eu  (3)

Starting materials: CuO, SrCO₃, Al(OH)₃, Eu₂O₃, and/or any combinationthereof.

The starting materials in the form of oxides, hydroxides, and/orcarbonates may be mixed in stoichiometric proportions together withsmall amounts of flux, e.g., H₃BO₃. The mixture may be fired in analumina crucible in a first step at about 1,200° C. for about one hour.After milling the pre-fired materials a second firing step at about1,450° C. in a reduced atmosphere for about 4 hours may be followed.After that the material may be milled, washed, dried and sieved. Theresulting luminescent material may have an emission maximum of about 494nm.

TABLE 1 copper containing Eu²⁺-activated aluminate compared with Eu²⁺-activated aluminate without copper at about 400 nm excitation wavelengthCompound Compound containing copper without copperCu_(0.02)Sr_(3.98)Al₁₄O₂₅: Eu Sr₄Al₁₄O₂₅: Eu Luminous density (%) 103.1100 Wavelength (nm) 494 493

Preparation of the Luminescent Material Having Formula (4)

Pb_(0.05)Sr_(3.95)Al₁₄O₂₅:Eu  (4)

Starting materials: PbO, SrCO₃, Al₂O₃, Eu₂O₃, and/or any combinationthereof.

The starting materials in form of very pure oxides, carbonates, or othercomponents which may decompose thermically into oxides, may be mixed instoichiometric proportion together with small amounts of flux, forexample, H₃BO₃. The mixture may be fired in an alumina crucible at about1,200° C. for about one hour in the air. After milling the pre-firedmaterials a second firing step at about 1,450° C. in air for about 2hours and in a reduced atmosphere for about 2 hours may be followed.Then the material may be milled, washed, dried, and sieved. Theresulting luminescent material may have an emission maximum of fromabout 494.5 nm.

TABLE 2 lead-containing Eu²⁺-activated aluminate compared withEu²⁺-activated aluminate without lead at about 400 nm excitationwavelength Compound Lead-containing compound without leadPb_(0.05)Sr_(3.95)Al₁₄O₂₅: Eu Sr₄Al₁₄O₂₅: Eu Luminous density (%) 101.4100 Wavelength (nm) 494.5 493

TABLE 3 optical properties of some copper-and/or lead-containingaluminates excitable by long wave ultraviolet and/or by visible lightand their luminous density in % at 400 nm excitation wavelength Peakwave length of lead- Luminous density at 400 nm and/or copper Possibleexcitation compared containing Peak wave length of excitation withcompounds not materials materials without Composition range(nm)containing copper/lead (%) (nm) lead/copper (nm)Cu_(0.5)Sr_(3.5)Al₁₄O₂₅: Eu 360-430 101.2 495 493Cu_(0.02)Sr_(3.98)Al₁₄O₂₅: Eu 360-430 103.1 494 493Pb_(0.05)Sr_(3.95)Al₁₄O₂₅: Eu 360-430 101.4 494.5 493Cu_(0.01)Sr_(3.99)Al_(13.995)Si_(0.005)O₂₅: 360-430 103 494 492 EuCu_(0.01)Sr_(3.395)Ba_(0.595)Al₁₄O₂₅: Eu, 360-430 100.8 494 493 DyPb_(0.05)Sr_(3.95)Al_(13.95)Ga_(0.05)O₂₅: Eu 360-430 101.5 494 494

Example 2

Luminescent materials for ultraviolet light or visible light excitationcomprise lead and/or copper doped aluminates according to the formula asfollows:

a(M′O).b(M″O).c(Al₂O₃).d(M′″₂O₃).e(M″″O₂).f(M′″″_(x)O_(y))  (5)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Be,Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′″ may beB, Ga, In, and/or any combination thereof; M″″ may be Si, Ge, Ti, Zr,Hf, and/or any combination thereof; M′″″ may be Bi, Sn, Sb, Sc, Y, La,Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or anycombination thereof; 0<a≦1; 0≦b≦2; 0<c≦8; 0≦d≦1; 0≦e≦1; 0<f≦2; 1≦x≦2;and 1≦y≦5.

The luminous peak and density of Example 2 are described in Table 7,which will be shown below.

Example of Preparation:

Preparation of the Luminescent Material Having Formula (6)

Cu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄:Eu  (6)

Starting materials: CuO, SrCO₃, Al₂O₃, SiO₂, Eu₂O₃, and/or anycombination thereof.

The starting materials in the form of, for example, pure oxides and/oras carbonates may be mixed in stoichiometric proportions together withsmall amounts of flux, for example, AlF₃. The mixture may be fired in analumina crucible at about 1,250° C. in a reduced atmosphere for about 3hours. After that the material may be milled, washed, dried and sieved.The resulting luminescent material may have an emission maximum of about521.5 nm.

TABLE 4 copper containing Eu²⁺-activated aluminate compared with Eu²⁺-activated aluminate without copper at about 400 nm excitation wavelengthCompound Compound containging copper without copperCu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄: Eu SrAl₂O₄: Eu Luminousdensity 106 100 (%) Wavelength (nm) 521.5 519

Preparation of the Luminescent Material Having Formula (7)

Cu_(0.12)BaMg_(1.88)Al₁₆O₂₇:Eu  (7)

Starting materials: CuO, MgO, BaCO₃, Al(OH)₃, Eu₂O₃, and/or anycombination thereof.

The starting materials in the form of, for example, pure oxides,hydroxides, and/or carbonates may be mixed in stoichiometric proportionstogether with small amounts of flux, for example, AlF₃. The mixture maybe fired in an alumina crucible at about 1,420° C. in a reducedatmosphere for about 2 hours. After that the material may be milled,washed, dried, and sieved. The resulting luminescent material may havean emission maximum of about 452 nm.

TABLE 5 copper-containing Eu²⁺-activated aluminate compared with coppernot doped Eu²⁺-activated aluminate at 400 nm excitation wavelengthCompound Comparison containing copper without copperCu_(0.12)BaMg_(1.88)Al₁₆O₂₇: Eu BaMg₂Al₁₆O₂₇: Eu Luminous density (%)101 100 Wavelength (nm) 452 450

Preparation of the Luminescent Material Having Formula (8)

Pb_(0.1)Sr_(0.9)Al₂O₄:Eu  (8)

Starting materials: PbO, SrCO₃, Al(OH)₃, Eu₂O₃, and/or any combinationthereof.

The starting materials in form of, for example, pure oxides, hydroxides,and/or carbonates may be mixed in stoichiometric proportions togetherwith small amounts of flux, for example, H₃BO₃. The mixture may be firedin an alumina crucible at about 1,000° C. for about 2 hours in the air.After milling the pre-fired materials a second firing step at about1,420° C. in the air for about 1 hour and in a reduced atmosphere forabout 2 hours may be followed. After that the material may be milled,washed, dried and sieved. The resulting luminescent material may have anemission maximum of about 521 nm.

TABLE 6 lead-containing Eu²⁺-activated aluminate compared with Eu²⁺-activated aluminate without lead at about 400 nm excitation wavelengthLead-containing compound Compound without lead Pb_(0.1)Sr_(0.9)Al₂O₄: EuSrAl₂O₄: Eu Luminous density (%) 102 100 Wavelength (nm) 521 519

Results obtained in regard to copper and/or lead doped aluminates areshown in table 7.

TABLE 7 optical properties of some copper-and/or lead-containingaluminates excitable by long wave ultraviolet and/or by visible lightand their luminous density in % at 400 nm excitation wavelength Peakwave Luminous density at length of Possible 400 nm excitationlead/copper excitation compared with doped Peak wave length of rangecopper/lead not doped materials materials without Composition (nm)compounds (%) (nm) lead/copper (nm)Cu_(0.05)Sr_(0.95)Al_(1.9997)Si_(0.0003)O₄: Eu 360-440 106   521.5 519Cu_(0.2)Mg_(0.7995)Li_(0.0005)Al_(1.9)Ga_(0.1)O₄: 360-440 101.2 482 480Eu, Dy Pb_(0.1)Sr_(0.9)Al₂O₄: Eu 360-440 102 521 519Cu_(0.05)BaMg_(1.95)Al₁₆O₂₇: Eu, Mn 360-400 100.5 451, 515 450, 515Cu_(0.12)BaMg_(1.88)Al₁₆O₂₇: Eu 360-400 101 452 450Cu_(0.01)BaMg_(0.99)Al₁₀O₁₇: Eu 360-400 102.5 451 449Pb_(0.1)BaMg_(0.9)Al_(9.5)Ga_(0.5)O₁₇: Eu, 360-400 100.8 448 450 DyPb_(0.08)Sr_(0.902)Al₂O₄: Eu, Dy 360-440 102.4 521 519Pb_(0.2)Sr_(0.8)Al₂O₄: Mn 360-440 100.8 658 655 Cu_(0.06)Sr_(0.94)Al₂O₄:Eu 360-440 102.3 521 519 Cu_(0.05)Ba_(0.94)Pb_(0.06)Mg_(0.95)Al₁₀O₁₇:360-440 100.4 451 449 Eu Pb_(0.3)Ba_(0.7)Cu_(0.1)Mg_(1.9)Al₁₆O₂₇: Eu360-400 100.8 452 450 Pb_(0.3)Ba_(0.7)Cu_(0.1)Mg_(1.9)Al₁₆O₂₇: Eu,360-400 100.4 452, 515 450, 515 Mn

Example 3

Luminescent materials for ultraviolet light or visible light excitationcomprise lead and/or copper doped silicates according to the formula asfollows:

a(M′O).b(M″O).c(M′″X).d(M′″₂O).e(M″″₂O₃).f(M′″″_(o)O_(p)).g(SiO₂).h(M″″″_(x)O_(y))  (9)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Be,Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M′″ may beLi, Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M″″ may beAl, Ga, In, and/or any combination thereof; M′″″ may be Ge, V, Nb, Ta,W, Mo, Ti, Zr, Hf, and/or any combination thereof; M″″″ may be Bi, Sn,Sb, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,and/or any combination thereof; X may be F, Cl, Br, I, and anycombination thereof; 0<a≦2; 0<b≦8; 0≦c≦4; 0≦d≦2; 0≦e≦2; 0≦f≦2; 0<g≦10;0<h≦5; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

The copper-containing silicates exemplarily described herein may, insome embodiments, contain SiO₄ and be characterized as having an Olivinestructure (orthorhombic) or β-K_(.2)SO₄ structure (orthorhombic);contain Si₂O₈ and be characterized as having a trigonal Glaserite(K₃Na(SO₄)₂) or monoclinic Merwinite structure; contain Si₂O₇ and becharacterized as having a tetragonal Ackermanite structure; contain SiO₅and be characterized as having a tetragonal structure; and/or containSi₂O₅ and be characterized as having an orthorhombic structure.

The superior luminous density of Example 3 can be seen below.

Example of Preparation:

Preparation of the Luminescent Material Having Formula (10)

Cu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄: Eu  (10)

Starting materials: CuO, SrCO₃, CaCO₃, SiO₂, Eu₂O₃, and/or anycombination thereof.

The starting materials in the form of pure oxides and/or carbonates maybe mixed in stoichiometric proportions together with small amounts offlux, for example, NH₄Cl. The mixture may be fired in an aluminacrucible at about 1,200° C. in an inert gas atmosphere (e.g., N₂ ornoble gas) for about 2 hours. Then the material may be milled. Afterthat, the material may be fired in an alumina crucible at about 1,200°C. in a slightly reduced atmosphere for about 2 hours. Then, thematerial may be milled, washed, dried, and sieved. The resultingluminescent material may have an emission maximum at about 592 nm.

TABLE 8 copper-containing Eu²⁺-activated silicate compared with Eu²⁺-activated silicate without copper at about 400 nm excitation wavelengthCopper-containing Compound without compound copperCu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄: Eu Sr_(1.7)Ca_(0.3)SiO₄: Eu Luminousdensity (%) 104 100 Wavelength (nm) 592 588

Preparation of the Luminescent Material Having Formula (11):

Cu_(0.2)Ba₂Zn_(0.2)Mg_(0.6)Si₂O₇:Eu  (11)

Starting materials: CuO, BaCO₃, ZnO, MgO, SiO₂, Eu₂O₃, and/or anycombination thereof.

The starting materials in the form of very pure oxides and carbonatesmay be mixed in stoichiometric proportions together with small amountsof flux, for example, NH₄Cl. In a first step the mixture may be fired inan alumina crucible at about 1,100° C. in a reduced atmosphere for about2 hours. Then the material may be milled. After that the material may befired in an alumina crucible at about 1,235° C. in a reduced atmospherefor about 2 hours. Then that the material may be milled, washed, driedand sieved. The resulting luminescent material may have an emissionmaximum at about 467 nm.

TABLE 9 copper-containing Eu²⁺-activated silicate compared withEu²⁺-activated silicate without copper at 400 nm excitation wavelengthCopper-containing compound Compound without copperCu_(0.2)Sr₂Zn_(0.2)Mg_(0.6)Si₂O₇: Eu Sr₂Zn₂Mg_(0.6)Si₂O₇: Eu Luminous101.5 100 density (%) Wavelength 467 465 (nm)

Preparation of the Luminescent Material Having Formula (12)

Pb_(0.1)BaO_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄:Eu  (12)

Starting materials: PbO, SrCO₃, BaCO₃, SiO₂, GeO₂, Eu₂O₃, and/or anycombination thereof.

The starting materials in the form of oxides and/or carbonates may bemixed in stoichiometric proportions together with small amounts of flux,for example, NH₄Cl. The mixture may be fired in an alumina crucible atabout 1,000° C. for about 2 hours in the air. After milling thepre-fired materials a second firing step at 1,220° C. in air for 4 hoursand in reducing atmosphere for 2 hours may be followed. After that thematerial may be milled, washed, dried and sieved. The resultingluminescent material may have an emission maximum at about 527 nm.

TABLE 10 lead-containing Eu²⁺-activated silicate compared withEu²⁺-activated silicate without lead at about 400 nm excitationwavelength Compound Lead-containing compound without leadPb_(0.1)Ba_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄: Eu BaSrSiO₄: EuLuminous 101.3 100 density (%) Wavelength (nm) 527 525

Preparation of the Luminescent Material Having Formula (13)

Pb_(0.25)Sr_(3.75)Si₃O₈Cl₄:Eu  (13)

Starting materials: PbO, SrCO₃, SrCl₂, SiO₂, Eu₂O₃, and any combinationthereof.

The starting materials in the form of oxides, chlorides, and/orcarbonates may be mixed in stoichiometric proportions together withsmall amounts of flux, for example, NH₄Cl. The mixture may be fired inan alumina crucible in a first step at about 1,100° C. for about 2 hoursin the air. After milling the pre-fired materials a second firing stepat about 1,220° C. in the air for about 4 hours and in a reducedatmosphere for about 1 hour may be followed. After that the material maybe milled, washed, dried and sieved. The resulting luminescent materialmay have an emission maximum at about 492 nm.

TABLE 11 lead-containing Eu²⁺-activated chlorosilicate compared withEu²⁺- activated chlorosilicate without lead at 400 nm excitationwavelength Lead-containing compound Compound without leadPb_(0.25)Sr_(3.75)Si₃O₈Cl₄: Eu Sr₄Si₃O₈Cl₄: Eu Luminous 100.6 100density (%) Wavelength (nm) 492 490

Results obtained with respect to copper- and/or lead-containingsilicates are shown in table 12.

TABLE 12 optical properties of some copper- and/or lead-containing rareearth activated silicates excitable by long wave ultraviolet and/or byvisible light and their luminous density in % at about 400 nm excitationwavelength Peak wave Luminous density at length Possible 400 nmexcitation of lead-and/or Peak wave length excitation compared withcopper- of materials range copper/lead not doped containing withoutComposition (nm) compounds (%) materials (nm) lead/copper (nm)Pb_(0.1)Ba_(0.95)Sr_(0.95)Si_(0.998)Ge_(0.002)O₄: 360-470 101.3 527 525Eu Cu_(0.02)(Ba,Sr,Ca,Zn)_(1.98)SiO₄: 360-500 108.2 565 560 EuCu_(0.05)Sr_(1.7)Ca_(0.25)SiO₄: Eu 360-470 104 592 588Cu_(0.05)Li_(0.002)Sr_(1.5)Ba_(0.448)SiO₄: 360-470 102.5 557 555 Gd, EuCu_(0.2)Sr₂Zn_(0.2)Mg_(0.6)Si₂O₇: Eu 360-450 101.5 467 465Cu_(0.02)Ba_(2.8)Sr_(0.2)Mg_(0.98)Si₂O₈: 360-420 100.8 440, 660 438, 660Eu, Mn Pb_(0.25)Sr_(3.75)Si₃O₈Cl₄: Eu 360-470 100.6 492 490Cu_(0.2)Ba_(2.2)Sr_(0.75)Pb_(0.05)Zn_(0.8)Si₂O₈: 360-430 100.8 448 445Eu Cu_(0.2)Ba₃Mg_(0.8)Si_(1.99)Ge_(0.01)O₈: 360-430 101 444 440 EuCu_(0.5)Zn_(0.5)Ba₂Ge_(0.2)Si_(1.8)O₇: Eu 360-420 102.5 435 433Cu_(0.8)Mg_(0.2)Ba₃Si₂O₈: Eu, Mn 360-430 103 438, 670 435, 670Pb_(0.15)Ba_(1.84)Zn_(0.01)Si_(0.99)Zr_(0.01)O₄: 360-500 101 512 510 EuCu_(0.2)Ba₅Ca_(2.8)Si₄O₁₆: Eu 360-470 101.8 495 491

Example 4

Luminescent materials for ultraviolet light or visible light excitationcomprise lead and/or copper-containing antimonates according to theformula as follows:

a(M′O).b(M″₂O).c(M′X).d(Sb₂O₅).e(M′″O).f(M″″_(x)O_(y))  (14)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li,Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be Be,Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may beBi, Sn, Sc, Y, La, Pr, Sm, Eu, Tb, Dy, Gd, and/or any combinationthereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2;0≦b≦2; 0≦c≦4; 0≧d≦8; 0≦e≦8; 0<f≦2; 1≦x≦2; and 1≦y≦5.

Examples of Preparation:

Preparation of the Luminescent Material Having Formula (15)

Cu_(0.2)Mg_(0.7)Li_(0.2)Sb₂O₇:Mn  (15)

Starting materials: CuO, MgO, Li₂O, Sb₂O₅, MnCO₃, and/or any combinationthereof.

The starting materials in the form of oxides may be mixed instoichiometric proportion together with small amounts of flux. In afirst step the mixture may be fired in an alumina crucible at about 985°C. in the air for about 2 hours. After pre-firing the material may bemilled again. In a second step the mixture may be fired in an aluminacrucible at about 1,200° C. in an atmosphere containing oxygen for about8 hours. After that the material may be milled, washed, dried andsieved. The resulting luminescent material may have an emission maximumat about 626 nm.

TABLE 13 copper-containing antimonate compared with antimonate withoutcopper at about 400 nm excitation wavelength Copper-containing compoundComparison without copper Cu_(0.2)Mg_(1.7)Li_(0.2)Sb₂O₇: MnMg₂Li_(0.2)Sb₂O₇: Mn Luminous 101.8 100 density (%) Wavelength 652 650(nm)

Preparation of the Luminescent Material Having Formula (16)

Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆  (16)

Starting materials: PbO, CaCO₃, SrCO₃, Sb₂O₅, and/or any combinationthereof.

The starting materials in the form of oxides and/or carbonates may bemixed in stoichiometric proportions together with small amounts of flux.In a first step the mixture may be fired in an alumina crucible at about975° C. in the air for about 2 hours. After pre-firing the material maybe milled again. In a second step the mixture may be fired in an aluminacrucible at about 1,175° C. in the air for about 4 hours and then in anoxygen-containing atmosphere for about 4 hours. After that the materialmay be milled, washed, dried and sieved. The resulting luminescentmaterial may have an emission maximum at about 637 nm.

TABLE 14 lead-containing antimonate compared with antimonate withoutlead at 400 nm excitation wavelength Lead-containing compound Compoundwithout lead Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆ Ca_(0.6)Sr_(0.4)Sb₂O₆Luminous 102 100 density (%) Wavelength (nm) 637 638

Results obtained in respect to copper- and/or lead-containingantimonates are shown in table 15.

TABLE 15 optical properties of some copper and/or lead-containingantimonates excitable by long wave ultraviolet and/or by visible lightand their luminous density in % at about 400 nm excitation wavelengthLuminous density at 400 nm Peak wave excitation length of compared withPeak wave length materials Possible copper/lead not of lead-and/orwithout excitation doped compounds copper-containing lead/copperComposition range (nm) (%) materials (nm) (nm)Pb_(0.2)Mg_(0.002)Ca_(1.798)Sb₂O₆F₂: Mn 360-400 102 645 649Cu_(0.15)Ca_(1.845)Sr_(0.005)Sb_(1.998)Si_(0.002)O₇: 360-400 101.5 660658 Mn Cu_(0.2)Mg_(1.7)Li_(0.2)Sb₂O₇: Mn 360-400 101.8 652 650Cu_(0.2)Pb_(0.01)Ca_(0.79)Sb_(1.98)Nb_(0.02)O₆: Mn 360-400 98.5 658 658Cu_(0.01)Ca_(1.99)Sb_(1.9995)V_(0.0005)O₇: Mn 360-400 100.5 660 657Pb_(0.006)Ca_(0.6)Sr_(0.394)Sb₂O₆ 360-400 102 637 638Cu_(0.02)Ca_(0.9)Sr_(0.5)Ba_(0.4)Mg_(0.18)Sb₂O₇ 360-400 102.5 649 645Pb_(0.198)Mg_(0.004)Ca_(1.798)Sb₂O₆F₂ 360-400 101.8 628 630

Example 5

Luminescent materials for ultraviolet light or visible light excitationcomprise lead- and/or copper-containing germanates and/or agermanate-silicates exemplarily characterized according to the formulaas follows:

a(M′O)b(M″₂O)c(M″X)dGeO₂e(M′″O)f(M″″₂O₃)g(M′″″_(o)O_(p))h(M″″″_(x)O_(y))  (17)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li,Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be Be,Mg, Ca, Sr, Ba, Zn, Cd, and/or any combination thereof; M″″ may be Sc,Y, B, Al, La, Ga, In, and/or any combination thereof; Mm′″″ may be Si,Ti, Zr, Mn, V, Nb, Ta, W, Mo, and/or any combination thereof; M″″″ maybe Bi, Sn, Pr, Sm, Eu, Gd, Dy, and/or any combination thereof; X may beF, Cl, Br, I, and/or any combination thereof; 0<a≦2; 0≦b≦2; 0≦c≦10;0≦d≦10; 0≦e≦14; 0≦f≦14; 0≦g≦10; 0≦h≦2; 1≦o≦2; 1≦p≦5; 1≦x≦2; and 1≦y≦5.

Example of Preparation:

Preparation of the Luminescent Material Having Formula (18)

Pb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄:Mn  (18)

Starting materials: PbO, CaCO₃, ZnO, GeO₂, SiO₂, MnCO₃, and/or anycombination thereof,

The starting materials in the form of oxides and/or carbonates may bemixed in stoichiometric proportions together with small amounts of flux,for example, NH₄Cl. In a first step the mixture may be fired in analumina crucible at about 1,200° C. in an oxygen-containing atmospherefor about 2 hours. Then, the material may be milled again. In a secondstep the mixture may be fired in an alumina crucible at about 1,200° C.in oxygen containing atmosphere for about 2 hours. After that thematerial may be milled, washed, dried and sieved. The resultingluminescent material may have an emission maximum at about 655 nm.

TABLE 16 lead-containing Mn-activated germanate compared withMn-activated germinate without lead at about 400 nm excitationwavelength Comparison without Copper-containing compound copperPb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄:Ca_(1.99)Zn_(0.01)Ge_(0.8)Si_(0.2)O₄: Mn Mn Luminous 101.5 100 density(%) Wavelength 655 657 (nm)

Preparation of the Luminescent Material Having Formula (19)

Cu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃:Mn  (19)

Starting materials: CuO, SrCO₃, GeO₂, SiO₂, MnCO₃, and/or anycombination thereof.

The starting materials in the form of oxides and/or carbonates may bemixed in stoichiometric proportions together with small amounts of flux,for example, NH₄Cl. In a first step the mixture may be fired in analumina crucible at about 1,100° C. in an oxygen-containing atmospherefor about 2 hours. Then, the material may be milled again. In a secondstep the mixture may be fired in an alumina crucible at about 1,180° C.in an oxygen-containing atmosphere for about 4 hours. After that thematerial may be milled, washed, dried and sieved.

The resulting luminescent material may have an emission maximum at about658 nm.

TABLE 17 copper-containing Mn-activated germanate-silicate compared withMn- activated germanate-silicate without copper at 400 nm excitationwavelength Compound copper-containing compound without copperCu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃: Mn SrGe_(0.6)Si_(0.4)O₃: MnLuminous density 103 100 (%) Wavelength (nm) 658 655

TABLE 18 optical properties of some copper and/or lead-containinggermanate- silicates excitable by long wave ultraviolet and/or byvisible light and their luminous density in % at about 400 nm excitationwavelength Luminous density at 400 nm excitation Peak wave Peak wavePossible compared with length of lead- length of materials excitationcopper/lead not and/or copper- without range containing containinglead/copper Composition (nm) compounds (%) materials (nm) (nm)Pb_(0.004)Ca_(1.99)Zn_(0.006)Ge_(0.8)Si_(0.2)O₄: Mn 360-400 101.5 655657 Pb_(0.002)Sr_(0.954)Ca_(1.044)Ge_(0.93)Si_(0.07)O₄: 360-400 101.5660 661 Mn Cu_(0.46)Sr_(0.54)Ge_(0.6)Si_(0.4)O₃: Mn 360-400 103 658 655Cu_(0.002)Sr_(0.998)Ba_(0.99)Ca_(0.01)Si_(0.98)Ge_(0.02)O₄: 360-470 102538 533 Eu Cu_(1.45)Mg_(26.55)Ge_(9.4)Si_(0.6)O₄₈: Mn 360-400 102 660657 Cu_(1.2)Mg_(26.8)Ge_(8.9)Si_(1.1)O₄₈: Mn 360-400 103.8 670 656Cu₄Mg₂₀Zn₄Ge₅Si_(2.5)O₃₈F₁₀: Mn 360-400 101.5 658 655Pb_(0.001)Ba_(0.849)Zn_(0.05)Sr_(1.1)Ge_(0.04)Si_(0.96)O₄: 360-470 101.8550 545 Eu Cu_(0.05)Mg_(4.95)GeO₆F₂: Mn 360-400 100.5 655 653Cu_(0.05)Mg_(3.95)GeO_(5.5)F: Mn 360-400 100.8 657 653

Example 6

Luminescent materials for ultraviolet light or visible light excitationcomprise lead and/or copper-containing phosphates exemplarilycharacterized according to the formula as follows:

a(M′O)b(M″₂O)c(M″X)dP₂O₅ e(M′″O)f(M″″₂O₃)g(M′″″O₂)h(M″″″_(x)O_(y))  (20)

wherein M′ may be Pb, Cu, and/or any combination thereof; M″ may be Li,Na, K, Rb, Cs, Au, Ag, and/or any combination thereof; M′″ may be Be,Mg, Ca, Sr, Ba, Zn, Cd, Mn, and/or any combination thereof; M″″ may beSc, Y, B, Al, La, Ga, In, and/or any combination thereof, Mm′″″ may beSi, Ge, Ti, Zr, Hf; V, Nb, Ta, W, Mo, and/or any combination thereof;M″″″ may be Bi, Sn, Pr, Sm, Eu, Gd, Dy, Ce, Tb, and/or any combinationthereof; X may be F, Cl, Br, I, and/or any combination thereof; 0<a≦2;0≦b≦12; 0≦c≦16; 0<d≦3; 0≦e≦5; 0≦f≦3; 0≦g≦2; 0<h≦2; 1≦x≦2; and 1≦y≦5.

The luminescent materials comprising the lead and/or copper-containingphosphates may be used as compounds for ultraviolet light in a lightemitting device.

Examples of Preparation:

Preparation of the Luminescent Material Having Formula (21)

Cu_(0.02)Ca_(4.98)(PO₄)₃Cl:Eu  (21)

Starting materials: CuO, CaCO₃, Ca₃(PO₄)₂, CaCl₂, Eu₂O₃, and/or anycombination thereof,

The starting materials in the form of oxides, phosphates, and/orcarbonates and chlorides may be mixed in stoichiometric proportionstogether with small amounts of flux. The mixture may be fired in analumina crucible at about 1,240° C. in reducing atmosphere for about 2hours. After that the material may be milled, washed, dried and sieved.The luminescent material may have an emission maximum at about 450 nm.

TABLE 19 copper-containing Eu²⁺-activated chlorophosphate compared withEu²⁺-activated chlorophosphate without copper at about 400 nm excitationwavelength Copper-containing Compound compound without copperCu_(0.02)Ca_(4.98)(PO₄)₃Cl: Eu Ca₅(PO₄)₃Cl: Eu Luminous density (%)101.5 100 Wavelength (nm) 450 447

TABLE 20 copper- and/or lead-containing phosphates excitable by longwave ultraviolet and/or by visible light and their luminous density in %at about 400 nm excitation wavelength Luminous density at 400 nm Peakwave length excitation compared of lead/copper- Peak wave lengthPossible with copper/lead not containing of materials excitation dopedcompounds materials without Composition range (nm) (%) (nm) lead/copper(nm) Cu_(0.02)Sr_(4.98)(PO₄)₃Cl: Eu 360-410 101.5 450 447Cu_(0.2)Mg_(0.8)BaP₂O₇: Eu, Mn 360-400 102 638 635Pb_(0.5)Sr_(1.5)P_(1.84)B_(0.16)O_(6.84): Eu 360-400 102 425 420Cu_(0.5)Mg_(0.5)Ba₂(P,Si)₂O₈: Eu 360-400 101 573 570Cu_(0.5)Sr_(9.5)(P,B)₆O₂₄Cl₂: Eu 360-410 102 460 456Cu_(0.5)Ba₃Sr_(6.5)P₆O₂₄(F,Cl)₂: 360-410 102 443 442 EuCu_(0.05)(Ca,Sr,Ba)_(4.95)P₃O₁₂Cl: 360-410 101.5 438, 641 435, 640 Eu,Mn Pb_(0.1)Ba_(2.9)P₂O₈: Eu 360-400 103 421 419

Lead- and/or copper-containing luminescent materials exemplarilydescribed above can be act as converter for light emitting devices, suchas ultraviolet as well as blue emitting LEDs, back lights and paintingpigments. They can convert the excitation wavelength from theultraviolet and blue light to longer visible wavelength. According tosome embodiments, one or more of the lead- and/or copper-containingluminescent materials exemplarily described above may be used or mixedto produce a luminescent material with a color temperature ranging fromabout 2,000K to about 8,0000K or about 10,000K and superior colorrendering index of greater than about 60 (e.g. between about 60 andabout 90, or greater than about 90, or between about 90 and about 95).Thus, for all color temperatures as well as for all color coordinatesinside of the white light coordinates, an appropriate luminescentmaterial or mixture thereof can be found.

1. A luminescent material for a light emitting diode (LED), comprising:a first compound including a host lattice and a luminescent ion withinthe host lattice, wherein the host lattice comprises first ions andoxygen, wherein a first portion of the first ions is substituted bydivalent copper ions, wherein the first compound emits light uponexcitation with ultraviolet light or visible light emitted by the LED,wherein the first compound has a trigonal Glaserite (K₃Na(SO₄)₂) crystalstructure, a monoclinic Merwinite crystal structure, a tetragonalcrystal structure, or an orthorhombic crystal structure, and wherein thefirst ions comprise at least one of Be, Mg, Ca, Sr, Ba, Zn, Cd and Mn.2. The luminescent material of claim 1, wherein the luminescent materialhas a color temperature ranging from about 2,000K to about 8,000K. 3.The luminescent material of claim 1, wherein the luminescent materialhas a color temperature of about 10,000K.
 4. The luminescent material ofclaim 1, wherein the luminescent material has a color rendering indexgreater than about
 60. 5. The luminescent material of claim 4, whereinthe luminescent material has a color rendering index between about 60and about
 90. 6. The luminescent material of claim 4, wherein theluminescent material has a color rendering index greater than about 90.7. The luminescent material of claim 1, wherein the luminescent ioncomprises at least one of Bi, Sn, Sb, Sc, Y, La, In, Ce, Pr, Nd, Pm, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
 8. The luminescent material ofclaim 1, wherein the first compound comprises a silicate.
 9. Theluminescent material of claim 8, wherein the first compound comprisesGe.